Flight Patterns —

SpaceX’s Dragon approaches the ISS tomorrow morning

The commercial craft will do a delicate tango with the Space Station.

Early Wednesday morning, SpaceX's Dragon spacecraft will carefully begin a docking process on the International Space Station to deliver supplies to and from the ISS. The cargo capsule launched on Sunday evening, and appeared to go off without a hitch. But on the morning after, a view of the Falcon 9 rocket booster showed one of the nine engines that powered the craft broke apart. Luckily, the other eight engines remained functional and sent Dragon into the desired preliminary orbit.

After reaching preliminary orbit, Dragon detached from Falcon 9's second stage and released its solar arrays to get close to the ISS. From here, SpaceX says its unmanned capsule will communicate via UHF (ultra-high frequency) signal and through the on-board crew-command panel, which will be receiving instructions from the (terrestrial) crew.

If all goes well, around 4:13am CT Dragon will burn its engines to reach within 250 m (820 ft) of the ISS. From there, Dragon will hold its position and engage its LiDAR and thermal imaging sensors to make sure the craft is aligned properly, checking LiDAR readings against thermal readings for accuracy. If all's well, the Dragon team in Hawthorne, California, and NASA's flight control team in Houston will let Dragon approach further.

Dragon will do another "go/no-go" check at 200 m (656 ft), and then one at 30 m (98 ft) from the station around 5:25am CT. If Dragon's Earth-based team gets the all clear from there, it will propel 10 m (32 ft) to the capture point, where the ISS crew will be notified that they can use the Space Station's robotic arm to reach for the capsule. If everything works according to plan, Dragon should dock on the ISS some 20 minutes after 6am CT tomorrow morning.

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20 Reader Comments

Approximately one minute and 19 seconds into last night's launch, the Falcon 9 rocket detected an anomaly on one first stage engine. Initial data suggests that one of the rocket's nine Merlin engines, Engine 1, lost pressure suddenly and an engine shutdown command was issued. We know the engine did not explode, because we continued to receive data from it. Panels designed to relieve pressure within the engine bay were ejected to protect the stage and other engines. Our review of flight data indicates that neither the rocket stage nor any of the other eight engines were negatively affected by this event.

[edit]: i didn't notice that the same press release was posted as an update on the previous story. still, i think it bears to clarify it here as well.

I appreciate their caution - but (from a ground-stomper) this seems a bit excessive. Simply program in a "near-collision" fail-safe - where the module briefly pulsed away.

While coming in, especially from a very slow 20m trajectory -- if the arm cannot capture the module, have THEN it slightly boost away.

Sorry for the "catch phrase" - but this is no longer "rocket science'! The over-abundance of caution far exceeds the chance of a meteor ripping the space station to shreds.

Unfortunately, this simply smacks of "saving the bathwater even if the baby was thrown out" caution,.

How?

There are people on the ISS, you know. If Dragon (an unmanned space vehicle) plows into it due to a computer glitch, they all die. And incidentally, SpaceX would likely be out of business (killing people in space is pretty much death as far as any contracts would be concerned).

This level of caution is why space travel has a (relatively) high safety record. And what do they lose? It takes another hour or two to dock? Oh no, don't bother to take a little extra time, just roll the dice on blowing the ISA up and killing everyone on board.

There are people on the ISA, you know. If Dragon (an unmanned space vehicle) plows into it due to a computer glitch, they all die. And incidentally, SpaceX would likely be out of business (killing people in space is pretty much death as far as any contracts would be concerned).

This level of caution is why space travel has a (relatively) high safety record. And what do they lose? It takes another hour or two to dock? Oh no, don't bother to take a little extra time, just roll the dice on blowing the ISA up and killing everyone on board.

Wasn't there some sort of satellite on the same rocket that was supposed to be deployed but now can not be?

The Orbcomm was deployed, but in a lower-than-planned orbit. Because of the first-stage engine failure, there wasn't enough propellant remaining in the upper stage after Dragon separation in order to satisfy NASA requirements to ensure that the upper stage could restart and push the Orbcomm to an orbit that would safely clear the ISS. There was an automated check on this residual propellant mass which caused the upper stage to abort the restart and deploy the Orbcomm in the parking orbit.

If not for the ISS collision avoidance measures, the upper stage could have restarted to insert the Orbcomm into a higher and more viable orbit notwithstanding the performance loss from the first-stage engine anomaly. But you can't take chances with the ISS. At the end of the day, Orbcomm is a secondary payload, and its requirements are serviced on a best-effort basis.

Tomorrow they get to open the hatch and get the icecream. Very smooth process today. 18 days on station then it will be released to return science samples to earth. Very nice to have the ability to return large amounts of stuff to earth again.

America has seemed to have lost it's fascination with space exploration, but reading this story gives me a tingle up my leg... How marvelous is it we can escape the bounds of our Earth-bound reality and venture into the heavens... Wonder if that's how it felt in the 1500's to board a wooden vessel and set sails on the high seas to lands unknown...

America has seemed to have lost it's fascination with space exploration, but reading this story gives me a tingle up my leg... How marvelous is it we can escape the bounds of our Earth-bound reality and venture into the heavens... Wonder if that’s how it felt in the 1500’sare to board a wooden vessel and set sails on the high seas to lands unknown…

We are well past the “unknown lands” stage, at least in earth orbits. The Mars expedition on the other hand, that is far more unknown lands. Of course we aren’t going to send anybody there till we have a much better idea than we had about the moon’s surface before we first sent people there.